Generally, the common input device of a computer includes a mouse, a keyboard, a trackball, and the like. For example, via the keyboard, the user may directly input characters and symbols into the computer. Consequently, the users and the manufacturers of the input devices pay more attention to keyboards. With increasing development of science and technology, the keyboard manufacturers make efforts in designing novel keyboards with diversified functions. Recently, an illuminated keyboard with an illuminating function has been disclosed in order to meet the users' requirements.
Hereinafter, the outward appearance of a conventional illuminated keyboard will be illustrated with reference to FIG. 1. FIG. 1 is a schematic top view illustrating the outward appearance of a conventional illuminated keyboard. As shown in FIG. 1, a plurality of keys 10 are installed on the surface of the conventional illuminated keyboard 1. These keys 10 are classified into some types, e.g. ordinary keys, numeric keys and function keys. When one or more keys are depressed by a user, a corresponding signal is issued to the computer, and thus the computer executes a function corresponding to the depressed key or keys. For example, when an ordinary key is depressed, a corresponding English letter or symbol is inputted into the computer. When a numeric key is depressed, a corresponding number is inputted into the computer. In addition, the function keys (F1˜F12) can be programmed to cause corresponding application programs to provide certain functions.
Hereinafter, the configurations and the functions of a conventional illuminated keyboard will be illustrated with reference to FIG. 2. Take one of the keys 10 for example. FIG. 2 is a schematic side view illustrating a key structure of a conventional illuminated keyboard. As shown in FIG. 2, the key structure 10 comprises a keycap 101, a scissors-type connecting member 102, an elastic element 103, a membrane switch circuit member 104, a base plate 105, a light-emitting element 106 and a light-shading plate 107. The keycap 101 may be touched and depressed by a user. The keycap 101 is connected with the scissors-type connecting member 102. The scissors-type connecting member 102 is arranged between the keycap 101 and the base plate 105. In addition, the scissors-type connecting member 102 is connected with the keycap 101 and the base plate 105. Through the scissors-type connecting member 102, the keycap 101 is movable upwardly or downwardly relative to the base plate 105. The membrane switch circuit member 104 is disposed on the base plate 105. The elastic element 103 is arranged between the keycap 101 and the membrane switch circuit member 104. When the keycap 101 is depressed, the elastic element 103 is deformed downwardly to trigger the membrane switch circuit member 104, so that the membrane switch circuit member 104 generates a key signal. The light-emitting element 106 is disposed under the keycap 101 for emitting light beams B. For example, the light-emitting element 106 is a light emitting diode (LED). The light-shading plate 107 is arranged between the keycap 101 and the membrane switch circuit member 104. In addition, the light-shading plate 107 is sustained against and supported by the scissors-type connecting member 102. The light-shading plate 107 has a light-shading region 1071 at the periphery thereof for sheltering the light beams B. For example, the light-shading plate 107 is made of Mylar. Moreover, by coating the periphery of the light-shading plate 107 with ink, the light-shading region 1071 is produced.
Please refer to FIG. 2 again. The light beams B emitted by the light-emitting element 106 are transmitted through the membrane switch circuit member 104, and directed to the keycap 101 and the gap between the keycap 101 and the membrane switch circuit member 104 so as to illuminate the key structure 10. In addition, the portions of the light beams B directed to the gap between the keycap 101 and the membrane switch circuit member 104 are sheltered by the light-shading region 1071 of the light-shading plate 107, so that the possibility of causing light leakage is minimized.
In a case that the key structure 10 is not depressed, as shown in FIG. 2, the keycap 101 of the key structure 10 is located at a first height (not shown). Whereas, when the key structure 10 is depressed, a depressing force is exerted on the keycap 101 to press against the elastic element 103, and thus the elastic element 103 is in a compressed state. As the keycap 101 is depressed, the scissors-type connecting member 102 is swung and changed to a folded state. At the same time, the elastic element 103 is deformed downwardly to trigger the membrane switch circuit member 104 overlying the base plate 105, so that the membrane switch circuit member 104 generates a key signal. In addition, the keycap 101 of the key structure 10 is lowered from the first height to a second height (not shown). When the keycap 101 is depressed to the end, the keycap 101 is moved downwardly to press against the light-shading plate 107, and thus the light-shading region 1071 of the light-shading plate 107 is contacted with the base plate 105. Under this circumstance, the gap between the keycap 101 and the base plate 105 is sheltered by the light-shading region 1071, and thus the light beams B fail to be transmitted through the light-shading region 1071 (see FIG. 3).
At the time when the depressing force exerted on the keycap 101 is eliminated, the keycap 101 will be moved upwardly is response to the restoring force of the elastic element 103. As the keycap 101 is moved upwardly, the scissors-type connecting member 102 responds to the traction of the keycap 101. Consequently, the keycap 101 is returned to its original position where the keycap 101 has not been depressed (i.e. at the first height).
Although the use of the light-shading plate 107 of the conventional illuminated keyboard 1 can prevent the light beams B from leaking to the region between any two adjacent keys 10, there are still some drawbacks. For example, since the keycap 101 is contacted with the light-shading plate 107 during the process of depressing the keycap 101, the hand feel of depressing the keycap 101 is usually unsatisfied. If the illuminated keyboard 1 has been used for a long term, the hand of the user is readily fatigued. Therefore, there is a need of providing a key structure for avoiding the light leakage problem and enhancing the hand feel.